Data is often communicated between components of a system via communication channels called buses. The capacity of a bus is defined by the number of bits of data that a bus can carry simultaneously. Data is communicated between buses or between buses and individual components of the system using switches. Electrical buses and switches are limited, however, in bandwidth capacity, speed, expandability, and susceptibility to cross-talk and interference.
Buses and switches are often integrated in a backplane bus architecture for various systems applications. An important attribute of a backplane bus architecture is the number of components that can be plugged into the backplane. The ability to interconnect individual components, sub-assemblies, processors, and systems, using a backplane, is an important aspect of systems integration. Many applications today require that the number of slot connections in a backplane bus architecture be expandable to facilitate the interconnection of additional components to perform functions conceived after the backplane was designed. The expandability of traditional backplane bus architectures is limited, however, by fixed bandwidth, fixed slot connections, and other electrical and mechanical constraints.